BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
Under SEV-ES, a IOIO_PROT intercept generates a #VC exception. VMGEXIT
must be used to allow the hypervisor to handle this intercept.
Add support to construct the required GHCB values to support a IOIO_PROT
NAE event. Parse the instruction that generated the #VC exception,
setting the required register values in the GHCB and creating the proper
SW_EXITINFO1 value in the GHCB.
Cc: Jordan Justen <jordan.l.jus...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Ard Biesheuvel <ard.biesheu...@arm.com>
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
OvmfPkg/Include/IndustryStandard/InstructionParsing.h | 83 +++
OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 560
+++++++++++++++++++-
2 files changed, 629 insertions(+), 14 deletions(-)
diff --git a/OvmfPkg/Include/IndustryStandard/InstructionParsing.h
b/OvmfPkg/Include/IndustryStandard/InstructionParsing.h
new file mode 100644
index 000000000000..149ff328e06c
--- /dev/null
+++ b/OvmfPkg/Include/IndustryStandard/InstructionParsing.h
@@ -0,0 +1,83 @@
+/** @file
+ Instruction parsing support definitions.
+
+ Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef __INSTRUCTION_PARSING_H__
+#define __INSTRUCTION_PARSING_H__
+
+#include <Base.h>
+#include <Uefi.h>
+
+//
+// Instruction REX prefix definition
+//
+typedef union {
+ struct {
+ UINT8 BitB:1;
+ UINT8 BitX:1;
+ UINT8 BitR:1;
+ UINT8 BitW:1;
+ UINT8 Rex:4;
+ } Bits;
+
+ UINT8 Uint8;
+} INSTRUCTION_REX_PREFIX;
+
+//
+// Instruction ModRM definition
+//
+typedef union {
+ struct {
+ UINT8 Rm:3;
+ UINT8 Reg:3;
+ UINT8 Mod:2;
+ } Bits;
+
+ UINT8 Uint8;
+} INSTRUCTION_MODRM;
+
+//
+// Instruction SIB definition
+//
+typedef union {
+ struct {
+ UINT8 Base:3;
+ UINT8 Index:3;
+ UINT8 Scale:2;
+ } Bits;
+
+ UINT8 Uint8;
+} INSTRUCTION_SIB;
+
+//
+// Legacy Instruction Prefixes
+//
+#define OVERRIDE_SEGMENT_CS 0x2E
+#define OVERRIDE_SEGMENT_DS 0x3E
+#define OVERRIDE_SEGMENT_ES 0x26
+#define OVERRIDE_SEGMENT_SS 0x36
+#define OVERRIDE_SEGMENT_FS 0x64
+#define OVERRIDE_SEGMENT_GS 0x65
+#define OVERRIDE_OPERAND_SIZE 0x66
+#define OVERRIDE_ADDRESS_SIZE 0x67
+#define LOCK_PREFIX 0xF0
+#define REPNZ_PREFIX 0xF2
+#define REPZ_PREFIX 0xF3
+
+//
+// REX Prefixes
+//
+#define REX_PREFIX_START 0x40
+#define REX_PREFIX_STOP 0x4F
+#define REX_64BIT_OPERAND_SIZE_MASK 0x08
+
+//
+// Two-byte Opcode Flag
+//
+#define TWO_BYTE_OPCODE_ESCAPE 0x0F
+
+#endif
diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
index b6a955ed8088..7c2bb12df10a 100644
--- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
@@ -11,6 +11,529 @@
#include <Library/BaseMemoryLib.h>
#include <Library/VmgExitLib.h>
#include <Register/Amd/Msr.h>
+#include <IndustryStandard/InstructionParsing.h>
+
+//
+// Instruction execution mode definition
+//
+typedef enum {
+ LongMode64Bit = 0,
+ LongModeCompat32Bit,
+ LongModeCompat16Bit,
+} SEV_ES_INSTRUCTION_MODE;
+
+//
+// Instruction size definition (for operand and address)
+//
+typedef enum {
+ Size8Bits = 0,
+ Size16Bits,
+ Size32Bits,
+ Size64Bits,
+} SEV_ES_INSTRUCTION_SIZE;
+
+//
+// Intruction segment definition
+//
+typedef enum {
+ SegmentEs = 0,
+ SegmentCs,
+ SegmentSs,
+ SegmentDs,
+ SegmentFs,
+ SegmentGs,
+} SEV_ES_INSTRUCTION_SEGMENT;
+
+//
+// Instruction rep function definition
+//
+typedef enum {
+ RepNone = 0,
+ RepZ,
+ RepNZ,
+} SEV_ES_INSTRUCTION_REP;
+
+typedef struct {
+ UINT8 Rm;
+ UINT8 Reg;
+ UINT8 Mod;
+} SEV_ES_INSTRUCTION_MODRM_EXT;
+
+typedef struct {
+ UINT8 Base;
+ UINT8 Index;
+ UINT8 Scale;
+} SEV_ES_INSTRUCTION_SIB_EXT;
+
+//
+// Instruction opcode definition
+//
+typedef struct {
+ SEV_ES_INSTRUCTION_MODRM_EXT ModRm;
+
+ SEV_ES_INSTRUCTION_SIB_EXT Sib;
+
+ UINTN RegData;
+ UINTN RmData;
+} SEV_ES_INSTRUCTION_OPCODE_EXT;
+
+//
+// Instruction parsing context definition
+//
+typedef struct {
+ GHCB *Ghcb;
+
+ SEV_ES_INSTRUCTION_MODE Mode;
+ SEV_ES_INSTRUCTION_SIZE DataSize;
+ SEV_ES_INSTRUCTION_SIZE AddrSize;
+ BOOLEAN SegmentSpecified;
+ SEV_ES_INSTRUCTION_SEGMENT Segment;
+ SEV_ES_INSTRUCTION_REP RepMode;
+
+ UINT8 *Begin;
+ UINT8 *End;
+
+ UINT8 *Prefixes;
+ UINT8 *OpCodes;
+ UINT8 *Displacement;
+ UINT8 *Immediate;
+
+ INSTRUCTION_REX_PREFIX RexPrefix;
+
+ BOOLEAN ModRmPresent;
+ INSTRUCTION_MODRM ModRm;
+
+ BOOLEAN SibPresent;
+ INSTRUCTION_SIB Sib;
+
+ UINTN PrefixSize;
+ UINTN OpCodeSize;
+ UINTN DisplacementSize;
+ UINTN ImmediateSize;
+
+ SEV_ES_INSTRUCTION_OPCODE_EXT Ext;
+} SEV_ES_INSTRUCTION_DATA;
+
+//
+// Non-automatic Exit function prototype
+//
+typedef
+UINT64
+(*NAE_EXIT) (
+ GHCB *Ghcb,
+ EFI_SYSTEM_CONTEXT_X64 *Regs,
+ SEV_ES_INSTRUCTION_DATA *InstructionData
+ );
+
+
+/**
+ Checks the GHCB to determine if the specified register has been marked valid.
+
+ The ValidBitmap area represents the areas of the GHCB that have been marked
+ valid. Return an indication of whether the area of the GHCB that holds the
+ specified register has been marked valid.
+
+ @param[in] Ghcb Pointer to the Guest-Hypervisor Communication Block
+ @param[in] Reg Offset in the GHCB of the register to check
+
+ @retval TRUE Register has been marked vald in the GHCB
+ @retval FALSE Register has not been marked valid in the GHCB
+
+**/
+STATIC
+BOOLEAN
+GhcbIsRegValid (
+ IN GHCB *Ghcb,
+ IN GHCB_REGISTER Reg
+ )
+{
+ UINT32 RegIndex;
+ UINT32 RegBit;
+
+ RegIndex = Reg / 8;
+ RegBit = Reg & 0x07;
+
+ return ((Ghcb->SaveArea.ValidBitmap[RegIndex] & (1 << RegBit)) != 0);
+}
+
+/**
+ Marks a register as valid in the GHCB.
+
+ The ValidBitmap area represents the areas of the GHCB that have been marked
+ valid. Set the area of the GHCB that holds the specified register as valid.
+
+ @param[in, out] Ghcb Pointer to the Guest-Hypervisor Communication Block
+ @param[in] Reg Offset in the GHCB of the register to mark valid
+
+**/
+STATIC
+VOID
+GhcbSetRegValid (
+ IN OUT GHCB *Ghcb,
+ IN GHCB_REGISTER Reg
+ )
+{
+ UINT32 RegIndex;
+ UINT32 RegBit;
+
+ RegIndex = Reg / 8;
+ RegBit = Reg & 0x07;
+
+ Ghcb->SaveArea.ValidBitmap[RegIndex] |= (1 << RegBit);
+}
+
+/**
+ Decode instruction prefixes.
+
+ Parse the instruction data to track the instruction prefixes that have
+ been used.
+
+ @param[in] Regs x64 processor context
+ @param[in, out] InstructionData Instruction parsing context
+
+**/
+STATIC
+VOID
+DecodePrefixes (
+ IN EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN OUT SEV_ES_INSTRUCTION_DATA *InstructionData
+ )
+{
+ SEV_ES_INSTRUCTION_MODE Mode;
+ SEV_ES_INSTRUCTION_SIZE ModeDataSize;
+ SEV_ES_INSTRUCTION_SIZE ModeAddrSize;
+ UINT8 *Byte;
+
+ //
+ // Always in 64-bit mode
+ //
+ Mode = LongMode64Bit;
+ ModeDataSize = Size32Bits;
+ ModeAddrSize = Size64Bits;
+
+ InstructionData->Mode = Mode;
+ InstructionData->DataSize = ModeDataSize;
+ InstructionData->AddrSize = ModeAddrSize;
+
+ InstructionData->Prefixes = InstructionData->Begin;
+
+ Byte = InstructionData->Prefixes;
+ for ( ; ; Byte++, InstructionData->PrefixSize++) {
+ //
+ // Check the 0x40 to 0x4F range using an if statement here since some
+ // compilers don't like the "case 0x40 ... 0x4F:" syntax. This avoids
+ // 16 case statements below.
+ //
+ if ((*Byte >= REX_PREFIX_START) && (*Byte <= REX_PREFIX_STOP)) {
+ InstructionData->RexPrefix.Uint8 = *Byte;
+ if ((*Byte & REX_64BIT_OPERAND_SIZE_MASK) != 0) {
+ InstructionData->DataSize = Size64Bits;
+ }
+ continue;
+ }
+
+ switch (*Byte) {
+ case OVERRIDE_SEGMENT_CS:
+ case OVERRIDE_SEGMENT_DS:
+ case OVERRIDE_SEGMENT_ES:
+ case OVERRIDE_SEGMENT_SS:
+ if (Mode != LongMode64Bit) {
+ InstructionData->SegmentSpecified = TRUE;
+ InstructionData->Segment = (*Byte >> 3) & 3;
+ }
+ break;
+
+ case OVERRIDE_SEGMENT_FS:
+ case OVERRIDE_SEGMENT_GS:
+ InstructionData->SegmentSpecified = TRUE;
+ InstructionData->Segment = *Byte & 7;
+ break;
+
+ case OVERRIDE_OPERAND_SIZE:
+ if (InstructionData->RexPrefix.Uint8 == 0) {
+ InstructionData->DataSize =
+ (Mode == LongMode64Bit) ? Size16Bits :
+ (Mode == LongModeCompat32Bit) ? Size16Bits :
+ (Mode == LongModeCompat16Bit) ? Size32Bits : 0;
+ }
+ break;
+
+ case OVERRIDE_ADDRESS_SIZE:
+ InstructionData->AddrSize =
+ (Mode == LongMode64Bit) ? Size32Bits :
+ (Mode == LongModeCompat32Bit) ? Size16Bits :
+ (Mode == LongModeCompat16Bit) ? Size32Bits : 0;
+ break;
+
+ case LOCK_PREFIX:
+ break;
+
+ case REPZ_PREFIX:
+ InstructionData->RepMode = RepZ;
+ break;
+
+ case REPNZ_PREFIX:
+ InstructionData->RepMode = RepNZ;
+ break;
+
+ default:
+ InstructionData->OpCodes = Byte;
+ InstructionData->OpCodeSize = (*Byte == TWO_BYTE_OPCODE_ESCAPE) ? 2 : 1;
+
+ InstructionData->End = Byte + InstructionData->OpCodeSize;
+ InstructionData->Displacement = InstructionData->End;
+ InstructionData->Immediate = InstructionData->End;
+ return;
+ }
+ }
+}
+
+/**
+ Determine instruction length
+
+ Return the total length of the parsed instruction.
+
+ @param[in] InstructionData Instruction parsing context
+
+ @return Length of parsed instruction
+
+**/
+STATIC
+UINT64
+InstructionLength (
+ IN SEV_ES_INSTRUCTION_DATA *InstructionData
+ )
+{
+ return (UINT64) (InstructionData->End - InstructionData->Begin);
+}
+
+/**
+ Initialize the instruction parsing context.
+
+ Initialize the instruction parsing context, which includes decoding the
+ instruction prefixes.
+
+ @param[in, out] InstructionData Instruction parsing context
+ @param[in] Ghcb Pointer to the Guest-Hypervisor
Communication
+ Block
+ @param[in] Regs x64 processor context
+
+**/
+STATIC
+VOID
+InitInstructionData (
+ IN OUT SEV_ES_INSTRUCTION_DATA *InstructionData,
+ IN GHCB *Ghcb,
+ IN EFI_SYSTEM_CONTEXT_X64 *Regs
+ )
+{
+ SetMem (InstructionData, sizeof (*InstructionData), 0);
+ InstructionData->Ghcb = Ghcb;
+ InstructionData->Begin = (UINT8 *) Regs->Rip;
+ InstructionData->End = (UINT8 *) Regs->Rip;
+
+ DecodePrefixes (Regs, InstructionData);
+}
+
+/**
+ Report an unsupported event to the hypervisor
+
+ Use the VMGEXIT support to report an unsupported event to the hypervisor.
+
+ @param[in] Ghcb Pointer to the Guest-Hypervisor Communication
+ Block
+ @param[in] Regs x64 processor context
+ @param[in] InstructionData Instruction parsing context
+
+ @return New exception value to propagate
+
+**/
+STATIC
+UINT64
+UnsupportedExit (
+ IN GHCB *Ghcb,
+ IN EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN SEV_ES_INSTRUCTION_DATA *InstructionData
+ )
+{
+ UINT64 Status;
+
+ Status = VmgExit (Ghcb, SVM_EXIT_UNSUPPORTED, Regs->ExceptionData, 0);
+ if (Status == 0) {
+ GHCB_EVENT_INJECTION Event;
+
+ Event.Uint64 = 0;
+ Event.Elements.Vector = GP_EXCEPTION;
+ Event.Elements.Type = GHCB_EVENT_INJECTION_TYPE_EXCEPTION;
+ Event.Elements.Valid = 1;
+
+ Status = Event.Uint64;
+ }
+
+ return Status;
+}
+
+/**
+ Build the IOIO event information.
+
+ The IOIO event information identifies the type of IO operation to be
performed
+ by the hypervisor. Build this information based on the instruction data.
+
+ @param[in] Regs x64 processor context
+ @param[in, out] InstructionData Instruction parsing context
+
+ @return IOIO event information value
+
+**/
+STATIC
+UINT64
+IoioExitInfo (
+ IN EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN OUT SEV_ES_INSTRUCTION_DATA *InstructionData
+ )
+{
+ UINT64 ExitInfo;
+
+ ExitInfo = 0;
+
+ switch (*(InstructionData->OpCodes)) {
+ //
+ // IN immediate opcodes
+ //
+ case 0xE4:
+ case 0xE5:
+ InstructionData->ImmediateSize = 1;
+ InstructionData->End++;
+ ExitInfo |= IOIO_TYPE_IN;
+ ExitInfo |= ((*(InstructionData->OpCodes + 1)) << 16);
+ break;
+
+ //
+ // OUT immediate opcodes
+ //
+ case 0xE6:
+ case 0xE7:
+ InstructionData->ImmediateSize = 1;
+ InstructionData->End++;
+ ExitInfo |= IOIO_TYPE_OUT;
+ ExitInfo |= ((*(InstructionData->OpCodes + 1)) << 16) | IOIO_TYPE_OUT;
+ break;
+
+ //
+ // IN register opcodes
+ //
+ case 0xEC:
+ case 0xED:
+ ExitInfo |= IOIO_TYPE_IN;
+ ExitInfo |= ((Regs->Rdx & 0xffff) << 16);
+ break;
+
+ //
+ // OUT register opcodes
+ //
+ case 0xEE:
+ case 0xEF:
+ ExitInfo |= IOIO_TYPE_OUT;
+ ExitInfo |= ((Regs->Rdx & 0xffff) << 16);
+ break;
+
+ default:
+ return 0;
+ }
+
+ switch (*(InstructionData->OpCodes)) {
+ //
+ // Single-byte opcodes
+ //
+ case 0xE4:
+ case 0xE6:
+ case 0xEC:
+ case 0xEE:
+ ExitInfo |= IOIO_DATA_8;
+ break;
+
+ //
+ // Length determined by instruction parsing
+ //
+ default:
+ ExitInfo |= (InstructionData->DataSize == Size16Bits) ? IOIO_DATA_16
+ : IOIO_DATA_32;
+ }
+
+ switch (InstructionData->AddrSize) {
+ case Size16Bits:
+ ExitInfo |= IOIO_ADDR_16;
+ break;
+
+ case Size32Bits:
+ ExitInfo |= IOIO_ADDR_32;
+ break;
+
+ case Size64Bits:
+ ExitInfo |= IOIO_ADDR_64;
+ break;
+
+ default:
+ break;
+ }
+
+ if (InstructionData->RepMode != 0) {
+ ExitInfo |= IOIO_REP;
+ }
+
+ return ExitInfo;
+}
+
+/**
+ Handle an IOIO event.
+
+ Use the VMGEXIT instruction to handle an IOIO event.
+
+ @param[in, out] Ghcb Pointer to the Guest-Hypervisor
Communication
+ Block
+ @param[in, out] Regs x64 processor context
+ @param[in] InstructionData Instruction parsing context
+
+ @return 0 Event handled successfully
+ @return Others New exception value to propagate
+
+**/
+STATIC
+UINT64
+IoioExit (
+ IN OUT GHCB *Ghcb,
+ IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN SEV_ES_INSTRUCTION_DATA *InstructionData
+ )
+{
+ UINT64 ExitInfo1, Status;
+
+ ExitInfo1 = IoioExitInfo (Regs, InstructionData);
+ if (ExitInfo1 == 0) {
+ return UnsupportedExit (Ghcb, Regs, InstructionData);
+ }
+
+ if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
+ Ghcb->SaveArea.Rax = 0;
+ } else {
+ CopyMem (&Ghcb->SaveArea.Rax, &Regs->Rax, IOIO_DATA_BYTES (ExitInfo1));
+ }
+ GhcbSetRegValid (Ghcb, GhcbRax);
+
+ Status = VmgExit (Ghcb, SVM_EXIT_IOIO_PROT, ExitInfo1, 0);
+ if (Status != 0) {
+ return Status;
+ }
+
+ if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
+ if (!GhcbIsRegValid (Ghcb, GhcbRax)) {
+ return UnsupportedExit (Ghcb, Regs, InstructionData);
+ }
+ CopyMem (&Regs->Rax, &Ghcb->SaveArea.Rax, IOIO_DATA_BYTES (ExitInfo1));
+ }
+
+ return 0;
+}
/**
Handle a #VC exception.
@@ -38,6 +561,8 @@ VmgExitHandleVc (
MSR_SEV_ES_GHCB_REGISTER Msr;
EFI_SYSTEM_CONTEXT_X64 *Regs;
GHCB *Ghcb;
+ NAE_EXIT NaeExit;
+ SEV_ES_INSTRUCTION_DATA InstructionData;
UINT64 ExitCode, Status;
EFI_STATUS VcRet;
@@ -54,24 +579,31 @@ VmgExitHandleVc (
ExitCode = Regs->ExceptionData;
switch (ExitCode) {
+ case SVM_EXIT_IOIO_PROT:
+ NaeExit = IoioExit;
+ break;
+
default:
- Status = VmgExit (Ghcb, SVM_EXIT_UNSUPPORTED, ExitCode, 0);
- if (Status == 0) {
- Regs->ExceptionData = 0;
- *ExceptionType = GP_EXCEPTION;
+ NaeExit = UnsupportedExit;
+ }
+
+ InitInstructionData (&InstructionData, Ghcb, Regs);
+
+ Status = NaeExit (Ghcb, Regs, &InstructionData);
+ if (Status == 0) {
+ Regs->Rip += InstructionLength (&InstructionData);
+ } else {
+ GHCB_EVENT_INJECTION Event;
+
+ Event.Uint64 = Status;
+ if (Event.Elements.ErrorCodeValid != 0) {
+ Regs->ExceptionData = Event.Elements.ErrorCode;
} else {
- GHCB_EVENT_INJECTION Event;
-
- Event.Uint64 = Status;
- if (Event.Elements.ErrorCodeValid != 0) {
- Regs->ExceptionData = Event.Elements.ErrorCode;
- } else {
- Regs->ExceptionData = 0;
- }
-
- *ExceptionType = Event.Elements.Vector;
+ Regs->ExceptionData = 0;
}
+ *ExceptionType = Event.Elements.Vector;
+
VcRet = EFI_PROTOCOL_ERROR;
}
--
2.27.0
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